JavaScript | parseFloat() with Examples

The parseFloat() is an inbuilt function in JavaScript which is used to accept the string and convert it into a floating point number. If the string does not contain a numeral value or If the first character of the string is not a Number then it returns NaN i.e, not a number. It actually returns a floating point number parsed up to that point where it encounters a character which is not a Number.
Syntax:

parseFloat(Value)

Parameters: It accepts a parameter “value” which contains a string which is converted to a floating point number.
Return value: It returns a floating point Number and if the first character of a string cannot be converted to a number then the function returns NaN i.e, not a number.
Example:

Input: var n = parseFloat("  2018  ");
Output: n=2018 (floating point Number)
The parseFloat() function ignores leading and trailing spaces and
returns the floating point Number of the string.

Input: var a = parseFloat("1000.04");
Output: now a = 1000.04(floating point Number)

JavaScript codes to show the working of this function:
Code #1:

<!DOCTYPE html> 
<html> 
  
<body> 
   <script> 
      // It ignores leading and trailing spaces. 
      a = parseFloat("  100  ") 
      document.write('parseFloat("  100  ") = ' +a +"<br>"); 
  
      // It returns floating point Number until 
      // it encounters Not a Number character 
      b = parseFloat("[email protected]") 
      document.write('parseFloat("[email protected]") = '+b +"<br>"); 
  
      // It returns NaN on Non numeral character 
      c = parseFloat("[email protected]") 
      document.write('parseFloat("[email protected]") = ' +c +"<br>"); 
  
      d = parseFloat("3.14") 
      document.write('parseFloat("3.14") = '+d +"<br>"); 
  
      // It returns only first Number it encounters 
      e = parseFloat("22 7 2018") 
      document.write('parseFloat("22 7 2018") = ' +e +"<br>"); 
        
    </script> 
  
</body> 
</html> 

Output:

parseFloat(" 100 ") = 100
parseFloat("[email protected]") = 2018
parseFloat("[email protected]") = NaN
parseFloat("3.14") = 3.14
parseFloat("22 7 2018") = 22

Code #2:
Using isNaN() function to test that converted values are valid number or not.

<!DOCTYPE html> 
<html> 
  
<body> 
   <script> 
      var x = parseFloat("3.14"); 
      if (isNaN(x)) 
          document.write("x is not a number" + "<br>"); 
      else
          document.write("x is a number" + "<br>"); 
  
      var y = parseFloat("geeksforgeeks"); 
      if (isNaN(y)) 
          document.write("y is not a number" + "<br>"); 
      else
          document.write("y is a number" + "<br>"); 
  
     // Difference between parseInt() and parseFloat() 
     var v1 = parseInt("3.14"); 
     var v2 = parseFloat("3.14"); 
  
     document.write('Using parseInt("3.14") = ' + v1 + "<br>"); 
     document.write('Using parseFloat("3.14") = ' + v2 + "<br>"); 
   </script> 
  
</body> 
</html>                   

Output:

x is a number
y is not a number
Using parseInt("3.14") = 3
Using parseFloat("3.14") = 3.14

JavaScript | parseFloat() with Examples

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